I have ran into an issue with the USB GPS dongles for the 4625 radios. I usually mount them to the back of the dish with the cord side down as that usually gives the best GPS signal vs using the provided plastic horizontal mount.
What can happen is if the GPS ever comes off the dish and is hanging upside down with the cord up that it will eventually get water inside the GPS which will make it no longer work.
I have seen this with 2 different GPS adapters. We get notified that GPS dongle is either not detected or GPS is not tracking any satellites. In both instances the GPS had fallen and was haning upside down for an unknown period of time, but both times it was after periods of either heavy rain or multiple days of rain.
Replace with a new one and all was good. Took GPS back to office and opened it up and in both instances there was significant water inside them. Looking at how it is made and gasketed there is not adequate sealing around the cord to prevent water ingress if not mounted horizontally or with the cord facing down.